Lowering your metabolism isn’t as straightforward as raising it, and most advice online focuses on the opposite goal. But there are real reasons people want to slow things down: difficulty gaining or maintaining weight, an overactive thyroid, or simply burning through energy faster than feels comfortable. Your resting metabolic rate, the calories your body burns just to keep you alive, is influenced by muscle mass, hormones, diet composition, activity level, and even the temperature around you. Some of these you can adjust deliberately.
Why Your Body Burns What It Burns
Your resting metabolic rate accounts for roughly 60 to 75 percent of the calories you use each day. The rest comes from physical activity and digesting food. Thyroid hormones are the primary driver of that baseline burn. Your thyroid releases two hormones, one largely inactive and one active, and the active form directly controls how fast every cell in your body uses energy. A feedback loop between your brain and thyroid keeps these levels stable, which is why metabolic rate tends to resist dramatic changes in either direction.
That said, your body does adapt. When conditions shift, whether through diet, exercise, sleep, or environment, your metabolism adjusts in measurable ways. The key is understanding which levers actually move the needle and which ones just feel like they should.
Eat Less Protein, More Fat
Every time you eat, your body spends energy breaking down and processing that food. This is called the thermic effect of food, and it varies dramatically by what’s on your plate. Protein costs the most to digest, increasing your metabolic rate by 15 to 30 percent of the calories consumed. Carbohydrates raise it by 5 to 10 percent. Fat is the cheapest to process, boosting your metabolic rate by only 0 to 3 percent.
If your goal is to lower overall energy expenditure, shifting your diet away from high-protein meals and toward higher-fat foods reduces the metabolic cost of digestion. This doesn’t mean abandoning protein entirely, since it’s essential for basic body functions, but a diet that leans more heavily on fats and simple carbohydrates will burn fewer calories during processing than one centered on lean protein and complex carbs.
Reduce Muscle Mass (Carefully)
Muscle tissue is metabolically expensive. Even at rest, it burns more calories per pound than fat tissue does. People with more lean mass have higher resting metabolic rates, full stop. This is one reason men typically burn more calories at rest than women of the same weight.
If you’re carrying significant muscle from strength training or athletics and want to lower your metabolic rate, reducing resistance training will gradually decrease lean mass. Your body won’t maintain muscle it doesn’t need. Over weeks and months, less muscle means a lower baseline calorie burn. This is a trade-off with real health implications, though, since muscle mass protects joints, supports mobility, and plays a role in blood sugar regulation. It’s worth being intentional rather than just stopping all activity.
How Exercise Triggers Metabolic Compensation
Here’s something counterintuitive: heavy aerobic exercise may actually lower your resting metabolic rate over time. Research on energy expenditure has found that the human body doesn’t simply stack exercise calories on top of resting calories the way most calorie calculators assume. Instead, it compensates. When researchers at Duke University and elsewhere measured total daily energy expenditure in people doing aerobic exercise programs, they found that total expenditure increased by only about 30 percent of what would be expected if exercise calories simply added up.
The body appears to dial down background processes, including resting metabolic rate and sleeping metabolic rate, to offset some of the energy spent on exercise. This compensation is especially strong when aerobic exercise is paired with calorie restriction, and in longer-duration studies, reductions in basal metabolic rate are a measurable part of the adjustment. Interestingly, resistance training triggers less of this compensation effect than cardio does.
So sustained aerobic exercise combined with moderate calorie restriction can train your body to run on less energy at rest. This is actually the mechanism behind the frustrating weight-loss plateaus dieters experience, but if your goal is a lower metabolic rate, it works in your favor.
Stay Warm
Your body burns extra calories to maintain its core temperature when the environment is cold. Metabolic rate rises steadily as ambient temperature drops below the thermoneutral zone, which for humans falls between roughly 89 and 102°F (32 to 39°C). Below that range, your body generates heat through shivering and other processes that cost energy.
Keeping your living and sleeping environment warm, dressing in layers, and avoiding prolonged cold exposure all minimize this thermogenic calorie burn. It’s a modest effect for most people, but it’s a real one, especially for those who live in cold climates or keep their homes cool.
Sleep and Metabolic Rate
The relationship between sleep and metabolism is less straightforward than many wellness sites suggest. Research from the American Heart Association found that when sleep is restricted, resting energy expenditure actually increases, largely because staying awake simply costs more energy than being asleep. The added hours of wakefulness drive up total calorie burn even if resting metabolic rate per hour doesn’t change much.
However, there’s a nuance worth noting. When people combine sleep restriction with a weight-loss diet, their resting metabolic rate drops more sharply than it does when they sleep a normal amount on the same diet. This suggests that sleep deprivation amplifies the body’s tendency to slow down its baseline burn during calorie restriction. For someone specifically trying to lower metabolic rate, though, the practical takeaway is that getting adequate sleep (7 to 9 hours) keeps your body in a more stable, lower-expenditure state than staying up late, since those extra waking hours burn more total energy.
When a High Metabolism Is a Medical Issue
Some people searching for ways to lower their metabolism are dealing with hyperthyroidism, a condition where the thyroid gland produces too much hormone and drives the metabolic rate abnormally high. Symptoms include unintentional weight loss, rapid heartbeat, tremors, anxiety, heat intolerance, and difficulty sleeping. If that sounds familiar, this isn’t something to manage with diet tweaks alone.
Treatment for hyperthyroidism typically starts with medication that prevents the thyroid from overproducing hormones. Symptoms usually begin improving within several weeks to months, and treatment courses generally last 12 to 18 months. In some cases, radioiodine therapy is used to shrink the gland, or surgery to remove part or all of the thyroid may be recommended. Once thyroid hormone levels normalize, metabolic rate comes back into a typical range, and the symptoms that come with running too hot resolve.
Putting It Together
For most people without a medical condition, the most effective combination for lowering metabolic rate involves reducing muscle mass through less resistance training, shifting dietary macros toward fat and away from protein, staying in warm environments, and allowing the body’s natural compensation mechanisms to kick in during sustained aerobic exercise. None of these changes are dramatic on their own, but they compound. Your body is built to adapt to the demands placed on it, and when those demands decrease, it learns to run more efficiently on less fuel.
Keep in mind that a lower metabolic rate means your body is less metabolically active overall. The same adaptations that reduce calorie burn also tend to reduce energy levels, body temperature regulation, and physical performance. It’s a package deal, so knowing exactly why you want a slower metabolism helps you decide how far to take these changes.